This invention relates to self-centering idler assemblies for reversably or bidirectionally training driven troughing conveyor belts.
In many applications conveyor belts are driven upon a train or series of supporting rollers with their center portion located beneath the belt sides. With this configuration materials can be conveyed upon the belt without substantial risk of falling from the sides thereof. Thus, such troughing conveyor belts are typically used, for example, in conveying ore in mining operations.
An ever present problem associated with the use of conveyor belts, and with troughing conveyor belts in particular, is the tendency of the belts to detrain and become misaligned with its supporting bed of rollers. The use of guard rails along their sides has failed to solve this problem due to the fraying thereby occasioned of the belt edges. Such rails also create a need for excessive power necessitated in overcoming intermittent frictional drag momentarily created by encounters of the belt sides with the rails.
In an effort to maintain alignment of troughing belts, mechanisms have been devised, as exemplified by that disclosed in U.S. Pat. No. 3,191,761, for mechanically aligning belt supporting rollers in those localities where the tendencies for the belt to become misaligned are identified in actual operation. This approach to the problem, however, has not proved satisfactory due to the tediousness required in effecting alignment. Furthermore, in many applications troughing belts are driven bidirectionally in which case a previously trained roller assembly will actually act to detrain the belt upon reversals in the direction of belt movement. Thus, each time the direction of belt movement is reversed, the roller assembly must again be mechanically aligned.
To overcome these problems mechanisms have been devised for effecting automatic training of troughing belts as exemplified in those disclosed in U.S. Pat. Nos. 2,983,364 and 3,240,321. Mechanisms of the type disclosed in the former patent, however, are deficient due to the fact that each lateral assembly of rollers is canted in tandem during automatic training. This results in a tendency of the mechanism to overtrain thereby creating wave-like or wobbling movement of the belts as they proceed down the line with successive roller assemblies tending to train the belt back and forth. Automatic training assemblies of the type shown in the latter patent have a principal deficiency in their complexity occasioned by the fact that the wing roller members in each assembly of lateral belt supporting roller sets are individually trained thereby providing a multiplicity of movable parts and pivot points which leads to extensive maintenance and insufficient longevity.
Accordingly, it is a general object of the present invention to provide an improved self-training idler assembly for troughing conveyor belts.
More specifically, it is an object of the present invention to provide a self-training idler assembly for a troughing conveyor belt adapted to be reversibly driven.
Another object of the invention is to provide a self-training idler assembly of relatively simple and economic construction.
Another object of the invention is to provide a self-training idler assembly for a troughing conveyor belt having a minimum of moving parts and minimal maintenance.
Yet another object of the invention is to provide a self-training idler assembly in which a single movement of an assembly of two wing rollers causes mutually convergent training of the roller thereby preventing overtraining of either individual roller.